Mobile communication has profoundly changed people's life, but people never stop pursuing higher-performance mobile communication. A 5th Generation (5G) mobile communications system emerges, so as to deal with an explosive growth of mobile data traffic, massive device connections, and various new emerging services and application scenarios in the future. As an important part of 5G, Internet of Things witnesses a rapid growth in market demand. Currently, the 3rd Generation Partnership Project (3GPP) is studying how to carry an Internet of Things (IoT) service based on a cellular network by designing a new air interface and making full use of a feature of a narrowband technology. This type of IoT is referred to as NB-IoT. Compared with a conventional cellular network, in an NB-IoT network, a service and a terminal device have the following requirements and features: a low service rate, a long period, massive connections, a low cost, low power consumption, and the like.
For the NB-IoT network, a system solution is re-designed in response to the foregoing requirements and features of the NB-IoT network, the service, and the terminal. A new access control mechanism is introduced in NB-IoT due to a low cost requirement. An access control parameter is placed in an independent system information block (SIB). FIG. 1 is a schematic diagram of NB-IoT access control. As shown in FIG. 1, a system message includes a master system message (Master information Block, MIB) that includes a most important system parameter of a system, a SIB 1 that carries cell access control information and scheduling information of another system information block, a SIB 2 for radio resource configuration, a newly added SIB_AC for access control, and other SIBs. When a network is lightly loaded and access control is not performed, an access control (AC) resource is not scheduled and the SIB_AC is not sent, either. When a network is overloaded and access control needs to be performed, an AC resource is scheduled and the SIB_AC needs to be sent. In this way, when an AC function is enabled or disabled, because scheduling information that is in the SIB 1 and that is corresponding to the AC function also changes, user equipment (UE) always needs to read the SIB 1 to obtain updated scheduling information when the access control function is enabled or disabled.
However, because NB-IoT supports a coverage enhancement feature and narrowband system bandwidth, and transmission time of a SIB 1 message is relatively long, the UE continuously performs detection and reception, and power consumption of the UE increases.